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- Build Old Style Indexes
Build Old Style Indexes¶
Important
Use this procedure only if you must have indexes that are compatible with a version of MongoDB earlier than 2.0.
MongoDB version 2.0 introduced the {v:1}
index format. MongoDB
versions 2.0 and later support both the {v:1}
format and the
earlier {v:0}
format.
MongoDB versions prior to 2.0, however, support only the {v:0}
format. If you need to roll back MongoDB to a version prior to 2.0,
you must drop and re-create your indexes.
To build pre-2.0 indexes, use the dropIndexes()
and ensureIndex()
methods. You cannot simply reindex
the collection. When you reindex on versions that only support
{v:0}
indexes, the v
fields in the index definition still hold
values of 1
, even though the indexes would now use the {v:0}
format. If you were to upgrade again to version 2.0 or later, these
indexes would not work.
Example
Suppose you rolled back from MongoDB 2.0 to MongoDB 1.8, and suppose
you had the following index on the items
collection:
The v
field tells you the index is a {v:1}
index, which
is incompatible with version 1.8.
To drop the index, issue the following command:
To recreate the index as a {v:0}
index, issue the following
command:
See also